Electric picture transmission



1929. w. SCHEPPMANN- ELECTRIC PICTURE TRANSMISSION Filed March 29, 1928DIIVQ:

iiiliiiili ill INVEIITOR Wilhelm Schema ma n n. flafi HTT KHEY PatentedAug. 27, 1929.

UNITED STATES 1,726,126 PATENT OFFICE.

WILHELM SCI-IEPPMANN, OF BERLIN-TEMPELHOF, GERMANY.

ELECTRIC PICTURE TRANSMISSION.

Application filed March 29, 1928, Serial No. 265,779, and in GermanyApril 5, 1927.

The present invention relates to electric picture transmission systems,e. g., those working according tothe telegraphic, or an equivalentprinciple.

The object of this invention is particularly directed to an improved andsimple means for reproducing the picture, drawing, or document at thereceiving station.

Another object of the present invention is to provide a reproductionmeans which is very simple and does not need further treatment-after thepicture has been received.

Still another object of the present invention is to provide a simplemeans for receiving pictures, drawings, and documents sentout bybroadcasting stations for amateurs.

My invention is more particularly described in the following disclosuretaken with reference to the appended drawing, which shows schematicallyan apparatus in the simplest form embodying the present invention, ofwhich Fig. 1 showsa side elevation, and

Fig. 2 shows a front view of a receiving apparatus in its simplest form.

The reproduction of pictures at a receiving station, even in a roughmanner, has always been connected with trouble andinconvenience.Well-known methods are those working mechanically whereby the individualpicture elements are printed by a printing mechanism magneticallyoperated by the picture signals. nother method of copying is that usinga photographic registrating paper. Still another method which has becomeknown, uses the chemical action on the registrating paper. This lattermethod, too, presents practical inconveniences in that the paper has toundergo subsequent chemical treatment.

According to my invention, I use as registration means a sheet of paperor similar material covered with a thin layer of wax or equivalentmaterial of a color diiferent from that of said paper. In a preferredembodiment the paper is of a darker color than the applied layer of wax.Only a small pressure on the layer exercised by a sharp tool operated bythe picture current impulses will suffice to remove or scratch off thelayer so that the paper will be laid open. Experi- I ments have shownthat by this method lines as thin as a hair may be produced in the waxlayer. This latter may be made so thin (about 1/100 to 2/100 cm), that avery slight pressure produced by a stylus operated by an armature or amembrane will produce a mark on the layer. The armature or membrane isactuated by the picture current impulses received from the transmittingstation. In the well-known telegraphic system these current impulses areof shorter or longer duration, and will produce corresponding shorter orlonger scratchings on the receiving paper, and thus build up thepicture.

In the drawings a preferred embodiment of my invention is represented ina schematic manner which is well adapted for the use in picturebroadcasting on account of its simplicity.

Similar reference numbers refer to similar elements. Numeral 1 is arotating cylinder moved at the same time lengthwise in the direction ofits axis. This cylinder is operated synchronously with a similarcylinder ar ranged at the transmitting station intended for scanning thepicture to be transmitted. This latter may be prepared by applying anon-conducting material to a conducting sheet to be mounted 1011 thetransmitting cylinder. A stylus or feeler scanning the picture on thetransmitting station in a spirallike manner opens and closes an electriccircuit and sends corresponding current impulses to the receivingstation. This transmission may be effected by means of wire or bywireless, as is well-known in the art. These current impulses energize areceiving magnet 4. The magnet 4 operates a lever 5 at the other end ofwhich a stylus 6 is attached. A spring 7 is provided to hold the leverin its zero position, i. e., the position at the time when coil 4 is notenergized. The registration paper 2 bearing the thin layer of wax 3 isfixed on the receiving cylinder 1. Each time a picture current impulsearrives from the sending station the stylus 6 is pressed against thepaper 2, scratching on the wax layer on that particular spot. Thus, thewhole picture, drawing, or document is gradually reconstructed.

The system described is very well adapted for transmitting so-calledblack and white pictures such as drawings, written or printed documents,weather maps, and is especially useful in wireless transmission forbroadcasting purposes on account of its simplicity and easy operation.An inclined straight line transmitted from the sending station wouldlook on the receiving sheet somewhat as shown at L in Fig. .2.

The operation of the device represented in the drawing may also be suchthat normally the stylus 6 is pressing on the registration paper, andthat an incoming picture current impulse will remove it therefrom. Thus,a negative picture with respect to that obtained before, will bereceived.

The synchronization of the sending and receiving cylinders may beeffected in any known manner which is not described here, as being outoffthe scope of this invention.

Having described my invention, what I believe to be new and desire tosecure and protect by Letters Patent of the United States 1s 1. Meansfor picture reproduction in elec tric' picture transmission systems,comprising a sheet of registration material having a dark paper, andmeans operated in accordance with the picture current impulses toscratch off said layer to directly produce a positive.

3. Means for reproduction of visual images by electric impulsescomprising a cylinder, a registration surface on said cylinder having adark colored background, a layer of Wax of light color compared to saidsurface on said surface, and means for recording the image elementscorresponding to said electric impulses by mechanical indentations onsaid wax layer whereby a positivepicture is produced.

4. Means for reproduction of visual images by electric impulsescomprising a cylinder, at registration surface on said cylinder having adark shade background, a layer of wax of light color compared to saidsurface on said surface, and means comprising an electrically operatedstylus for producing mechanical indentations of said wax layer inaccordance to said image elements whereby a positive picture isproduced.

In testimony whereof I have aflixed my signature.

WILHELM SCHEPPMANN.

